#!/usr/bin/env python3
"""Runtime probe for real AKShare NAV dates.

This is the "can the host actually reach AKShare?" check that backs the
`GET /api/market/nav-dates` endpoint. It talks to AKShare directly (no mocks),
memoises the akshare frame lookup with functools.lru_cache, and prints a single
JSON object on success:

    {"code": "000001", "dates": ["2026-09-21", "2026-09-18", ...]}

On any failure (missing dependency, network error, unusable payload) it writes a
clear message to stderr and exits non-zero so callers can treat it as a skipped /
unavailable probe instead of inventing data.
"""

import argparse
import functools
import json
import sys

import akshare as ak


@functools.lru_cache(maxsize=8)
def fetch_nav_frame(code: str):
    """Fetch the since-inception unit-NAV frame for a fund (cached per code)."""
    return ak.fund_open_fund_info_em(
        symbol=code,
        indicator="单位净值走势",
        period="成立来",
    )


def recent_nav_dates(code: str, limit: int = 5):
    """Return the most recent distinct NAV dates (descending) for a fund code."""
    if len(code) != 6 or not code.isdigit():
        raise ValueError("fund code must contain exactly six digits")

    frame = fetch_nav_frame(code)
    if frame is None or frame.empty:
        raise RuntimeError(f"AKShare returned no NAV observations for {code}")

    column = "净值日期"
    if column not in frame.columns:
        raise RuntimeError(f"AKShare payload for {code} is missing the {column} column")

    dates = []
    for value in frame[column].tolist():
        text = str(value).strip()[:10]
        if len(text) == 10 and text not in dates:
            dates.append(text)

    dates.sort(reverse=True)
    return dates[:limit]


def main():
    parser = argparse.ArgumentParser(
        description="Probe real AKShare NAV dates for a fund code",
    )
    parser.add_argument("--code", default="000001")
    parser.add_argument("--limit", type=int, default=5)
    args = parser.parse_args()

    try:
        dates = recent_nav_dates(args.code, args.limit)
    except Exception as error:  # noqa: BLE001 - probe reports the concrete reason
        print(f"AKShare NAV-date probe failed for {args.code}: {error}", file=sys.stderr)
        return 2

    if not dates:
        print(f"AKShare NAV-date probe found no dates for {args.code}", file=sys.stderr)
        return 2

    json.dump({"code": args.code, "dates": dates}, sys.stdout, ensure_ascii=False)
    sys.stdout.write("\n")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())